High-strength cellulose–polyacrylamide hydrogels: Mechanical behavior and structure depending on the type of cellulose

Abstract

Two types of high-strength composite hydrogels possessing the structure of interpenetrating polymer networks were synthesized via free-radical polymerization of acrylamide carried out straight within the matrix of plant or bacterial cellulose swollen in the reactive solution. The mechanical behavior of synthesized hydrogels subjected to the action of compressive deformations with different amplitude values was studied. The analysis of the stress-strain curves of compression tests of the hydrogels of both types obtained in different test conditions demonstrates the substantial difference in their mechanical behavior. Both the plant cellulose-based and bacterial cellulose-based hydrogels withstand successfully the compression with the amplitude up to 80 %, but the bacterial cellulose-based compositions demonstrate in the multiple compression tests the substantial decrease of the mechanical stiffness caused by the action of compressions. This effect takes place straightly during the multiple cyclic compression tests or in the course of relaxation of previously compressed samples in water in unloaded state during 2-3 days after the first compressive tests. Being subjected to the action of the extremely sever compression (up to 80 %) the bacterial cellulose-based hydrogel varies greatly its mechanical behavior: during the subsequent compressions the stiffness of the material keeps extremely small (as compared to that registered in the first compression) up to the deformations as high as 50-60 % with the dramatic increase of the stiffness during the further loading. This unusual effect can be explained by the deep reorganization of the intermolecular structure of the material with the stress-induced reorientation of cellulose micro-fibrils, fragmentation and disintegration of the interpenetrating networks structure with the breaking of the covalent bonds in the matrix polymer. Submicron-and micron-scale specific features of structures of composite hydrogels of both types were studied by cryo-scanning electron microscopy to explain the peculiarities of observed mechanical effects.

DLP 3D Printing Meets Lignocellulosic Biopolymers: Carboxymethyl Cellulose Inks for 3D Biocompatible Hydrogels

“…An M-CMC/water/LAP formulation was used to print 3D cylindrical shaped hydrogels that were used for the evaluation of the compressive elastic modulus of the hydrogels. Figure 4B reports one representative stress-strain curve; the value of the compressive modulus was calculated in two ranges of deformation, according to the method reported by Buyanov et al [51]. The slope of the first linear region correspond to a Young's modulus of 32 kPa, while increasing the imposed deformation, the modulus increases up to 84 kPa.…”

“…Figure 4 B reports one representative stress–strain curve; the value of the compressive modulus was calculated in two ranges of deformation, according to the method reported by Buyanov et al [ 51 ]. The slope of the first linear region correspond to a Young’s modulus of 32 kPa, while increasing the imposed deformation, the modulus increases up to 84 kPa.…”

Preparation of poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropan sulfonic acid)‐g‐Carboxymethyl cellulose/Titanium dioxide hydrogels and modeling of their swelling capacity and mechanic strength behaviors by response surface method technique

“…Hydrogels are three‐dimensional (3D) cross‐linked elastic and hydrophilic networks that can absorb a large amount of water without undergoing dissolution. [ 1‐3 ] They have numerous applications in biomedical related fields as artificial muscles, [ 4 ] wound dressing materials, [ 5 ] drug delivery systems, [ 6 ] contact lens, [ 7 ] elastic medical devices, [ 8 ] and biosensors. [ 9 ]…”

Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

“…Cellulose is the most common polymer that is also biocompatible and biodegradable, and due to its complex hierarchical supramolecular structure, crystalline cellulose has unique properties: Cellulose nanofibrils and nanocrystals have excellent mechanical properties comparable to those of steel [ 21 , 22 ], making cellulose an excellent candidate for reinforcing polymeric materials [ 23 , 24 ]. The biological and physical properties discussed above make cellulose a versatile material for medical applications, particularly for wound dressings [ 25 , 26 ] and for diverse tissue scaffolds [ 27 , 28 , 29 ]. Materials based on cellulose modified by poly(anionic acids) are also used for the development of metal sorption membranes [ 30 ], equipment for virus-capturing [ 31 ], and bone scaffolds [ 9 ].…”